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A darker Black Widow?

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darker widow
4K views 24 replies 5 participants last post by  Ericglo 
#1 ·
What would be the recommended method to make Black Widow a bit darker?

I am pondering getting the new Acer H6500 projector which has good light output and I would really like to have some ambient light tolerance.
 
#2 ·
Welcome to HTS! :wave:

While it's possible to darken BW™ a bit by adding Liquitex BASICS 'Ivory Black' (a max. of 10% IIRC), we actually are in the process of developing darker versions of BW™. However, it a slow process since we have to do it in our spare time and that is at a premium nowadays (life seems to speed up not slow down :gulp:).
 
#3 ·
Thanks Harpmaker. Is that "Ivory Black" the same as a bone black pigment?

If you use up to 10% of the Ivory Black, what gain do you expect to achieve? BW is around 0.88, but what if I want to get down to 0.4?

Have you looked into black mica pigments? "http://www.amazon.com/Dark-Black-Mica-Powder-Metallic/dp/B0040E981E" (sorry, can't post auto-links yet, only 2nd post)

How about a darker base coat?

I know, lots of questions, but I like to explore the possibilities. :D
 
#4 ·
Thanks Harpmaker. Is that "Ivory Black" the same as a bone black pigment?
Yes; the other major black pigment in artist acrylics is 'Mars Black' which is a synthetic iron oxide. 'Ivory Black' will result in a blue push to the mix if too much is used and the blue isn't corrected for, but it is less blue than 'Mars Black'.

If you use up to 10% of the Ivory Black, what gain do you expect to achieve? BW is around 0.88, but what if I want to get down to 0.4?
Unfortunately, screen gain isn't something that can be guessed with any accuracy at all; too much goes into what produces it. First you have the gloss level of the paint base being used and then you have the added gain from any reflective element added to the mix. I could tell you what gain (or rather how much light the surface would absorb) for a Lambertian surface (a surface that reflects light in all directions equally), but when you throw paint gloss and reflective particles into the equation gain simply must be measured. It turns out that a N7 Lambertian surface would have a gain of 0.4 (would reflect 40% of the light that hits it). A N7 neutral gray paint, even most flat finish latex paints, would have a gain slightly higher than this since even they have some gloss. The more gloss and/or the more reflective particles that are added the higher the peak gain of the mix will be, but it doesn't take much to be too much and then hot spotting, or other negative optical artifacts, becomes a problem.

Have you looked into black mica pigments? "http://www.amazon.com/Dark-Black-Mica-Powder-Metallic/dp/B0040E981E" (sorry, can't post auto-links yet, only 2nd post)
Yes, but when you start adding color to mica you decrease the reflectiveness. This is from the description of the pigment you give the link for: "This mica powder is a matte with a very slight shimmer". All the colored mica powders I have seen are either for coloring automotive paint (thus having large flakes that won't work for a screen) or making cosmetic powders (these lose most of their reflective qualities when added to paint).

How about a darker base coat?
This is the way we will try to go with our darker BW™ mixes.

I know, lots of questions, but I like to explore the possibilities. :D
We don't mind questions, questions are good. :T
 
#10 · (Edited)
...and just to pique your interest...

These screenies were taken during 2005 (I believe :dontknow:) of my version of a black screen. This formula used silver and pearl mica based pigments plus various red, green, and blue pigments. There is NO titanium dioxide in the mix. Behr flat deep base was used to carry the pigments. This coat was spray painted over a standard primer coat. The projector is a LL style DIY job pushing maybe 250 to 300 lumens, floor mounted. Black screen is on the left, BOC on the right. First pic is with lights off. The "lights on" shots are obvious. The boxes holding up the screen are 18" wide so that puts the diagonal measurement around 75". All of the ambient lighting was coming from the right side of the screen. Pictures were taken from a seated viewing position (AKA on the couch:bigsmile:). I hope I remembered everything...was 6 years ago.







Inspiration for a new avatar :eek:
 
#13 ·
Ok, I ordered a new projector...ViewSonic Pro8200, one of the sub-$1000 1080p DLP units. A review at Projector Central states that it puts out 1145 lumens in the "Dark Room" setting in low lamp mode. I intend to run with these settings, or something close to it, to extend the lamp life. The projector will be ceiling mounted.

I intend to have a 92" diagonal 16:9 ratio screen. This would give me 45.5 footlamberts on a unity gain screen.

I want to use Black Widow, but with a gain of 0.88, it would give me 40.1 footlamberts.

Based on previous posts, my plan would be to paint a darker neutral gray base coat and then paint a top coat of Black Widow.

Any suggestions for the neutral gray base coat? How dark do I need to go?
 
#14 ·
I made the mistake of reading "base coat" as "base paint" before, sorry about that. The color of the base coat (the paint that BW™ will be applied over) will have little to do with the appearance and performance of the BW™ screen. All of our mixes are as opaque as we can make them so very little light makes it through 2 rolled coats (~4 sprayed coats) of paint.

To get a darker BW™ screen you need to darken the base paint used to make BW™. If you are interested in trying such a mix I'll start a thread in the DIY Screen Development forum. This experimental mix would be N6.6, have the same amount of aluminum in it and would be neutral.

With so much light hitting your screen you don't really need a reflectively enhanced mix like BW™, an OTS neutral gray would work fine. A paint tinted to match Glidden 'Veil' (~N7.5) would work well. Whenever you use a reflectively enhanced mix there is always the possibility that you may see some graininess in the image depending on the brightness of the image and how close your viewing distance is.
 
#19 ·
No, I haven't dismissed it totally, but one also has to consider the color of any ambient light sources and how they will reflect off such a screen. That is what makes the problem more complex and from what I know now, likely impossible with the available range of pigments. However, if you can filter certain wavelengths out of your ambient light sources...then maybe...but that is another can of worms altogether.
 
#21 ·
I doubt it. If you take a look at the spectrum analysis done here on Silver Fire, you can see that the peaks and valleys are in the wrong places. I realized a month or two after my initial trials that there really isn't a good combination of pigments to put peaks right at R,G,B wavelenths and valleys at all other wavelengths. The spectral responses are too broad. With the addition of Cyan, Magenta, Yellow and "White" color wheel segments on DLP projectors, it's a futile exercise.

I'm surprised that the AVS'ers haven't been clever enough to mix a purple pigment (red and blue reflected) and a green pigment to cut down on the number of different pigments in their mix. This is something I looked into years ago but couldn't achieve the peaks and valleys that I wanted so I never disclosed it to the DIY world. However, this idea could possibly be used to achieve a neutral color balance.
 
#22 ·
I'm considering a projector for a small room that probably isn't really suitable for one, but I'm hung up on the idea of a 2.35:1 screen to ensure that movies are suitably immersive - my concern with a plasma is just that you get used to the size and then movies still seem small even though it would be a substantial improvement from where we are now.

My problem is that the tiny screen results in very high ft-L values - 24 in 2.35:1 config and if I zoom out to 16:9 I get 35+. So, the idea of a darker BW screen is intriguing. Paint is cheap so I do intend to try one of the identified neutral grey colors, but the additional ambient light rejection of the BW formulation is still attractive.

Being a projector newbie I'm hoping that dialing down the contrast as part of a calibration pass will help, but I'm not sure whether that's really possible without crushing things.
 
#23 ·
I understand the desire for 2.35:1. Thought about going the same route. However, I am hoping that the darker BW™ N6.4 will render the annoying top and bottom "black" bars, much less annoying than on a traditional screen. Then I won't have to mess with zoom or an anamorphic lens setup.:D
 
#24 · (Edited)
For me, 2.35:1 is pretty much the entire lure of a PJ - it's not that I mind the bars, just that I want to prioritize the 'wow' factor to movies. A 2.35 CIH setup allows me to do that, and actually suits our limited space very well since we actually have more width than height.
It'll be a bit of time before I can get around to screen samples, but I'll switch over to the 'development' thread since I definitely think I'll try out the darker version in addition to the standard. Ordered the PJ (Mits HC4000) yesterday, but I don't expect to get much more than DOA / sanity check with the wife done in the next couple weeks due to a busy schedule.
I plan to try to spray this with my Earlex HVLP rig, but it'll be my first experiment with it so it may be a disaster
 
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